I’m looking for a set of filters for black and white photography. Which filters are most useful and then which are the next set of filters that I should consider buying if I have extra money?

The most useful filters for black-and-white photography in film or digital are the Tiffen Yellow 8, which is best for natural looking clouds against blue skies, the Green 11, which yields more pleasing skin tones outdoors and reveals the details in foliage, and the Red 25 which creates dramatic cloud effects. Once you have these we would strongly recommend a Tiffen Circular Polarizer, a variable effect filter which can be used to alter contrast, bring out clouds, and minimize reflections on glass or water when used in bright sunlight.